You can bet on it: When it comes to predictions for Vermont's iconic fall foliage, no one has a corner on the market.

You're in good company.

One of the state's more avid and informed observers of the phenomenon, Department of Forests, Parks and Recreation Commissioner Michael Snyder, has been out of town recently and is unavailable for comment.

Maybe he's out gathering clues?

Other folks are, and with varying degrees of botanical scrutiny and wishful thinking.

Weather in these parts can turn on a dime, and Parsons cautioned against die-hard optimism: "I remember reading the National Weather Service forecaster discussion one fall when they said something along the lines of: 'the foliage viewing being good as the leaves blow 30 mph past the windshield in the rain.' "

For a more thorough scientific understanding of what variables are at play in the fall pallet, Parsons recommended a summary on the U.S. National Arboretum website.

The arboretum's analysis begins with the Big Three: temperature, sunlight, and soil moisture.

So what's the best recipe?

"A growing season with ample moisture that is followed by a rather dry, cool, sunny autumn that is marked by warm days and cool but frostless nights provides the best weather conditions for development of the brightest fall colors," the arboretum experts enthuse.

The reasons are complex, and in some ways, brutal. Ideal conditions for great fall foliage correspond to the worst possible conditions for the production of chlorophyl — the green we celebrate (perhaps even worship) in the summer.

The arboretum also offers warning signs for less-than-spectacular autumnal color:

• Freezing temperatures halt leaves' production of some pigments; early frosts cut a season short.

• Drought during the growing season often causes leaves to fall before they can crank out the bright pigments.

• A fall without wind and rain is generally a good thing, as far as leaf-peepers are concerned.

Marie Ambusk, who coordinates the South Burlington-based TREEage urban forestry and master gardener projects, tossed out a couple other variables: tree type and genetic variation can spin hillsides into different color wheels.

Ambusk also tossed out a couple of certainties: when it comes to predictions of seasonal splendor, "there is no perfect formula" and the quest for formulas "is a very interesting topic that we Vermonters like to discuss."

Effects of more rapid global warming "have greatly complicated the delicate balance of this phenomenon," she added.

Another astute tree-watcher, Barbara Mines, sits on the board of nonprofit Branch Out Burlington, began her prediction with a long "Hmmmm."

"It's been a fairly mild summer — so why not a spectacular foliage? I think its going to be the best foliage ever," Mines declared.

She paused for a second and added: "What do you think?"

Contact Joel Banner Baird at 660-1843 or joelbaird@FreePressMedia.com. Follow him on Twitter at www.twitter.com/vtgoingup